Electric measuring instrument.



W E PORTER ELECTRICAL MEASURING INSTRUMENT.

APPLICATION FILED MAY 26- I916.

Patented May 21 tel;

lnvenort WH lat-d E. Por- 5 UNITED STATES PATENT OFFICE.

WILLARD E. PORTER, OF LYNN, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented May 21, 1918.

Application filed May 26, 1916. Serial No. 100,130.

To all whom it may concern:

Be it known that I, WILLARD E. PORTER, a citizen of the United States residin at Lynn, in the county of Essex, tate of ssachusetts, have invented certain new and useful Improvements in Electrical Measuring Instruments, of which the following is a specification.

My invention relates to electrical measuring instrumentsfand particularly to electrical measuring instruments of the D urson :11 ty e.

(Jbneraily, he invention aims to provide an improved electrical measuring instrument and particularly an improved instrument of simple construction having few parts designed to be assembled in a convenient and inexpensive manner. The principal object of the invention is to provide an mex Jen'sive but at the same time accurate and re iable electric measuring instrument of the DArsonval type. A further object of the invention is to provide a simple and inexpensive construction of electrical measuring instrument particularly adapted to be embodied in instruments of relatively small size. Other objects of the invention will be brought out in the course of the following description.

The invention itself and the construction and mode of 0 Jerution of an electrical instrumentembo ying the same will behest understood by reference to the accompanying drawings and following description of such an instrument, while the novel features of the invention which I believe to be patentably characteristicthereof are definitely indicated in the appended claims.

In the accompanying drawings, Figure 1 is a top plan view of an electrical measuring instrument embodying the invention; Figs. 2, 3 and 5 are views partly in section showing the principal features of construction of the instrument; Fig. 4 is a sectional view taken along the section line Hoffl'Fig. 3; and'Figs. 6, 7, 8 and 9 are views illustrating certain details of the instruments cohstructlou.

The operative elements of the instrument illustrated in the accompanying drnuings are secured to a circular back casing member 10 of sheet metal or other suitable material. A screw-threaded supporting post 11 threaded on the post pole pieces, but its ends or clrcular configuration,

is secured in an suitable manner at the center of the member 10. A circular plate 12 of insulating material, such as sheet fiber, covers the bottom of the member 10. Inasmuch as I prefer to make the plate 12 of fiber I shall hereinafter refer to the same as a fiber plate. A portion of the fiberrrplate 12 is cutaway, as indicated by reference nu moral 13, for the accommodation of a zeroshiftin device, as will be more fully ex- Elainecf hereinafter. Two binding posts 14 aving an inte ral square nut- 15 at their inner ends extend throu h registering holes in the member 10, fiber plate 12 and an external fiber strip 16. The holes in the fiber members 12 and 16 are of slightly smaller diameter than the corresponding hole in the member 10, and each binding post is firmly secured to the member 10 by a nut 17 (Fig. 7). Each of the binding posts is thus insulated from the member 10.. A second circular plate 18, of fibbr or other insulating material, having square holes of the same size as the square nuts 15, is positioned on top of the fiber plate 12.

Three supporting studs 20 are secured to the member 10 and extend through suitable holes in the fiber plates 12 its 18.1 A circular permanent ma net 21 rests upon the studs 20. A yoke 22 1s slipped o'ter the supporting post 11 and is provided with upwardly extending ehds 23ndapted to rest on diametrically opposite parts of the top surface of the magnet 21. A nut 24 is screw- 11 and is designed to securely clamp the magnet between the studs 20 and the yoke 22. The magnet 21 has no are given a curved as best seen in Fig. 8 of the drawings.

A cylindrical shell or tube 25 is securely positioned between the circular ends of the permanent magnet 21. A s herical magnetic core 26 is positioned wi hin the shell 25 and between the ends of the magnet 21. Preferably, the sp erical core 26 is a steel such, for exam le, as is used for ballbearings. A bolt 2 and cooperating nuts 28 having spacing collars 29 serve to secure sition with respect to the. magnet 21 by means of a enrred plate having an ear 3] ex ending into an indentation in one of lhe outer edges ol" the ma. net 21, as will be Clearly understood by re erence to Figs. 8 and .J ot the drawings.

'tln i:-- het| 25 has cut away portions at eaeh of its ends beyond the eorrespondin planes of the top and bottom surfaees of tie magnet .41. wherel. y two oppositely positioned l to ieetiunn are provided at eaeh end ol the flit it. Each of the tour projeetiou 2%.) has an inwardly extending tongue 3t 'lhese tongues are preferably formed by slitting the material of the projections to produce the desired configuration of the tongue." and then forcing the part constituting the tongue inwardly, as will be clearly under stood by reterenee to Figs. 2, 2, and l of the drawings.

eireular cap 37 is mounted on the two rojrrtions at eaeh end of the shell 2 gewel serew is senew-threaded in eaeh cap 37. A not 39 ha ring a. shoulder upon whieh l'lfd: a spring elip -'i0 is threaded on the inner end oii eaeh jewel screw 38 and is held against rotation with respect to the jewel 1 1mm; by means of a pin it fastened in the map 3? and extending into a. hole in the. nut 39 (Fig. i}. The cap and jewel screw are secureiy heid on the projeetions'by forcing the ends of the spring clip beneath the tongues. In assembling the instrument. the cap 37, jewel. screw 38, not 39 and spring olip at are first seeured together, whereupon the ends ol the spring clip can be most eonvenientiy forced beneath the tongues an by providing two holes 43 in each eap through which two pins on a suitable punch can be inserted to force the ends of the spring elip downwardly, thereby so diminishing the distance between the ends of the Clips that the cap and assembled elements can be properly positioned, whereupon the punch is with drawn and the ends of the spring rlip engage beneath the tongues.

The moving element of the instrument comprises a circular current carrying coil 45 Wound on a suitable frame of conduit-ting ma terial, such as alumimnn, and provided with two pivot shafts 46 whose pivot points are designed to bear in the jewels at the inner ends of the jewel screws 38, as will be clearly understood from an inspection of Fig. I, of the drawings, 7

A pointer 4.7 is secured to the upper pivot shaft 46 and is adapted to sweep across a suitable scale 48. The scale 48 is carried on a circular scale plate 49 seemed to the top of the post 11 by a screw 50.

Spiral control springs are seeured at, their inner ends to the pivot shafts l6 and at their outer ends to studs or pins 56 his; tened in the eaps 37. Fhe springs 5-? also serve to conduct the eurrent to be measured to the movable coil "to of the, instrument in the well understood manner. When the shell 23 is assembled in the inslriunent two oppositely 11 ositioned pins (it) secured to and extending upwardly from a gear til projeet into the holes it in the lower nap ill.

The gear (31 rests upon a spacing plate (i2 which in turn rests on the member 10. The gear lit and spacing plate Uzi are seeured t the illetl llivl It) by a bolt (33 and cooperating nut it. The head of the nut. (ll has a recess (if; for the aoeounnodation ol' the outer end of the lower jewel crew 38, as will be understood by reference to i igs. :2 and 5 of the drawings. The bolt 63 forms a shaft upon which the gear 61 ean be rotated. A pinion (it? meshes with the gear G1 and is also mounted on the plate 62 and has an elon' gated shaft 67 extending throu h the rim of the member 10. The end 0 the shaft (37 is slotted for the accommodation of a screwdriver, and it will be observed that the pinion and gear ean be conveniently rotated from without the instrument casing by means of the slotted-timid shaft 67.

The angle. through which the gear 61 ran be rotated by the pinion (it; is limited by omitting Certain of the teeth of the gear, as shown in Fig. 5, so that the active portion of the gear is in eftert seotor-shaptal. Unmeshing of the gear 61 and pinion U6 is prerented by two spring arms 68 which engage the pins on the gear 61 when the gear is turned to one or the other. as the case may be, of its limiting positions. The spling arms 68 are the ends of a U-shaped wire member positioned about the post 11 and held in position against the side of the eutout portion 13 of the lower fiber plate 12 by the top tiber plate in. The gear 61 and pinion 66 constitute the Zero-shifting device of my present instrument. By turning the shaft 37 in one direetion or the other the gear 61 is also turned. and through the engagement of the pins (30 with the holes 43 of the lower cap 37 thi rap is moved with respect to its cooperating projeetions 30. This results in a corresponding movement of the control spring stud 5t; and hence an adjustment oi the tension of the lower eontrol spring Zerwshifting devices of the type herein illustrated and described are (a'nered in my eopending applieation lor Letters Patent of the United States. Serial No. 1:,200, filed Mar. 18, 1913.

The manner of seeuring the eontrol sprint studs 56 ii. the eaps 37 sothat the studs are insulated. from the raps will be understood by referent-e to Fig. i of the drawings. l laeh st ad 56 has a nut 70 integral therewith or secured thereto in any suitable manner. The out To is positioned in a eireular (lltltllber T1 in the eapIiT; The greatest diameter of the nut Tliis amaller than the diameter of the ehamber TI, and the top and bottom surfaces of the nut are covered by washers 72 of the same diameter as the chamber 71.. The washers 72 are of insulating material, such for example, as thin sheet mica. 1 metal washer 73 is positioned on the outer insulating washer 72 and the washers and stud 5b are securely held in position by forcing the material of the cap 37 over the edge of the metal washer 73. It will be observed from Fig. 6 that the registering holes in the metal washer 73 and in the cap 37 through which the stud 56 extends are of larger diameter than the stud. As previously stated the control springs 55 are electrically connected to the terminals of the current carrying coil 45 of the movin elementv of the instrument, and, according y, the. control spring studs 56 are adapted to be electricall connected to the s uare nuts 15 of the bin ing posts 14, as Wlll be 'Well understood by those skilled in the art.

It will be evident from the foregoing de scription that the instrument of my present invention is of the well known DArsonval type having a movable current carrying coil positioned in an air gap formed between the ends or poles of a permanent magnet and a cooperating magnetic core. and the mode of operation of such an instrument is so well understood that no further description of the operation of the im )roved instrument of my present invention 1s deemed necessary. The permanent magnet of my improved iustrumcnt has no pole pieces, which results in a material saving in the cost of manufacture of the instrument. The moving element of the instrument and the spherical magnetic core are all carried by the non-magnetic tubular member or shell. secured between the polefaces of the permanent magnet. It will be observed that the spherical magnetic core is supported by the tubular non-magnetic member along an axis substantially in the plane of the permanent magnet and at right angles to the line between the ends of the magnet, while the axis about which the moving element is pivoted is at right angles to both the supporting axis of the splurical core and the line between the ends of the. magnet. The various parts are mounted on the tubular non-magnetic supporting mem her in a manner assuring convenience. act-u racy and low cost in assembling. in fact it, will be obvious to those skilled in the art that I have provided an instrument of tremcly simple construction and one Those cost oi manufacture is relatively low.

I have herein shown and des ribed a par ticular embodiment of my invention for the purpose of explaining its principle and ill strating its applications. but numerous modifications of the details of ermstruction thcrcof and other embmliments oi the invention will presentthemselves to those skilled in the art. I. therefore, wish to cover by the lollowing claims all modifications within the spirit of the invention.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. An electrical measuring instrument comprising a permanent magnet having curved ends with an identation in one end, a cylindrical shell positioned between the curved ends of said magnet, a magnetic core mounted within said shell and between the ends of said magnet, a member secured to said shell and having an ear registering with said indentation for preventing relative movement of the shell and magnet, and a moving element having a coil positioned within said shelland around said core.

2. An electrical measuring instrument comprising a permanent magnet having curved ends, a cylindrical shell positioned between the curved ends of said magnet with its axis substantiall at right angles to the line between the endh of the magnet, a magnetic core mounted within said shell and between the" ends of said magnet, means secured to said shell and engaging said magnet for preventing relative movement of the shell and magnet, and a moving element having a coil positioned Within said shell and around said core.

3. 'An electrical measuring instrument comprising a permanent magnet having curved ends, a cylindrical shell positioned between the curved ends of said magnet with its axis substantially at right angles to the line between the en s of the magnet. a magnetic core mounted within said shell and be tween the ends of said magnet, means for preventing relative displacement of said shell and magnet, and a moving element having a coil positioned within said shell and around said core.

4. An electrical measuring instrument comprising a permanent magnet having curved ends with an indentation in one end, a cylindrical shell of non-magnetic material positioned between the curved ends of said magnet, a s iherical magnetic core positioned within said shell and between the endsof said magnet, a plate mounted on said shell and having an ear registering with said in dentation for preventing relative movement of the shell and magnet, a bolt adapted to. secure the shell and the core and the plate in their respective operative positions, and a moving element having a circular coil positioned within said shell and around said core.

5. An elcctricai measuring instrmnent comprising a permanent magnet having curved ends. a cylindrical shell positioned between the curved ends of said magnet with its axis substantially at right angles to the line between the ends of the magnet. a spherical magnetic core mounted within said shell and between the ends of said magnet, and :1

moving element supported by said shell and having a circular C(Jll positioned within the shell and around said core.

6. An eleetri a1 measuring instrument comprising a permanent magnet, a cylindri- "al shell of non-ma netic material secured between the ends 0 said magnet with its axis substantially at right angles to the line between the ends of the magnet, a spherical magnetic core positionedbetween the ends of said magnet, means for supporting said core from said shell. a moving element having a circular coil positioned within the shell and around said core. and means secured to the ends of said shell for pivotallv mounting said moving element.

7. An electrical measuring inslrmnent. comprising a permanent; magnet, a tubular non-magnetic member positioned between the ends of said magnet and having an inner wall of circular section with its axis sub stantially at right angles to the line between the ends of the magnet. a spherical mag netic core supported by said member along an axis substantially in the plane of the magnet and at right angles to the line between the ends of the magnet. said core being positioned within the member and be tween the ends of the magnet. and a eireular current-carryinn coil surrounding said core and pivotally mounted for movement about an axis at right angles to the supporting axis of said core and at right angles to the line between the ends of said magnet.

8. An electrical measuring inatrument comprising a permanent magnet, a tubular nonmagnetic member positioned between the ends of said magnet with its axis substantially at right angles to the line between the ends of the magnet and having an inner wall of circular section, a bolt extending through said member and positioned substantially in the plane of the magnet and at right angles to the line between the ends of the magnet. a spherical magnetic core mounted on said bolt and uniformly spaced from the inner Wall of said member, and a circular current-carrying coil surrounding said core and pivotally supported by said member for movement about an axis at right angles to said bolt and at right angles to the. line between the ends of said magnet.

9. An electrical measuring instriunent comprising a permanent magnet. a tubular non-magnetic member positioned between the ends of said magnet with its axis substantially at right angles to the line between the ends of the magnet and having: an inner wall of circular section. a spherical magnetic core supported by said member and positioned within the. member and between the ends of the magnet. and a circular currentearrying: coil surrounding said core and pirotally supported by said member.

in. An electrical measuring instrument romprising a. permanent magnet, a tubular non-magnetic member positioned between the ends olf said magnet with its axis substantially at right angles to the line between the ends of the magnet and having an inner wall of circular section, a bolt extending through said member and positioned substantialb in the plane of the magnet and at right angles to the line between the ends of the magnet a steel ball mounted on said bolt and uniformly spared from the inner wall of said member. a moving element pivotally supptu-ted by said member for movcment betneeu the hall and the ends of said magnet about an axis at right angles to said bolt and at right angles to the line. between the ends of the magnet. and a circular current-carrying coil mounted on said moving elen'ient.

11. An electrical measuring instrumenU comprising a permanent magnet. a tubular non-magnetic member positioned between the ends of said magnet. two inwardly extending and oppositely positioned tonguea near each end of said member, a rap mounted on each end of said member. a resilient element secured to each cap and projecting v beneath the two tongues near the corre sponding end of the member for securing the cap to the member. a pivot bearing carried by each cap. and a moving element mounted between hfllil pivot bearings.

12. All electrical measuring instrument roluprising a permanent magnet. a cylindrical shell of litllkltltlglltilt' material positioned between the ends of said magnet. a magnetic core carried by said hell and positioned between the ends of said magnet, two inwardly extemling and oppositely positioned tongues near each end of said shell. said tongues being integral with the material of the shell. a cap mounted on each end of said shell. a resilient element secured to each cap and projecting beneath the two tongues near the corresponding end of the shell for securing the cap to the shell, a pivot. bearing carried by each cap, and a moving element mounted l'letn'een sald pivot bearings.

13. An electrical measuring instrument comprising a permanent magnet a tubular non-magnetio member positioned between the ends of said magnet two inwardly extending aniloppositely positioned tongues near each end of said member. a cap mounted on each end of said member. a pivot hearing screw-tilreaded in each cap, a resilient member mounted on each pivot bearing, each pivot bearing having a shoulder cooperating with the cap for securing the resilient element to the cap, the resilient element of each cap projecting beneath the two tongues near the corresponding end of the member for securing the cap to the member. and a moving element mounted between said pivot bearings.

14, An electrical measuring instrument comprising a permanent magnet, a screwthrcaded pivot bearing having a shoulder, a resilient element mounted on said shoulder, a cap threaded on said pivot bearing so that the resilient element is held between the cap and shoulder, a tubular non-magnetic member positioned between the ends of said magnet, two inwardly extending and oppositely positioned tongues near one end of said member, said cap being mounted on one end of said member and said resilient element projecting beneath said two tongues for securing the cap to the member, a sec- 0nd pivot bearing, and a moving element mounted between said pivot bearings.

15. An electrical; measuring instrument comprising a pern'ianent magnet, a screwthreuded pivot bearing having a shoulder, a resilient clement mounted on said shoulder, a cap threaded on said pivot bearing so that the resilient element is held bet ween the cap and said shoulder, a tubular nonmagnetic member positioned between the ends of said magnet, two in ardly extending and oppo sitoly positioned tongues near one end of said member, said cap being mounted on one end of said member and said resilient element projecting beneath said two tongues for securing the cap to the member, a second pivot bearing, a moving clcn'xent mounted between said pivot bearings, a controi spring stud secured to said cap and insulated there from, and a control spring secured to said stud and to said moving element.

16. An electrical measuring instrument comprising a permanent magnet, a screwthreaded pivot bearing having a shoulder, a resilient clement mounted. on said shoulder. a cap threaded on said pivot bearing so that the resilient element held between the cap and said shoulder, a tubular nonmagnetic member positioned between the ends of said magnet, two inwardly extending and oppositely positioned tongues near one end of said member, said cap bein mounted on one end of said member an said resilient element projecting beneath said two tongues for securing the cap to the member, a second pivot bearing, a moving element mounted between said pivot bearings, a control spring secured to said cap and to said moving element, and a zero shifting means for moving said cap with respect to said member.

17. An electrical measuring instrument comprising a permanent magnet, a tubular non-magnetic member positioned between the ends of said magnet a cap mounted on each 'end of said member, a pivot bearing carried by each ca a moving element mounted between sai pivot bearings, a control spring secured to said moving element and to one of said caps, and a zero shifting means for moving said last mentioned cap i net'ic supporting member, a magnetic core supported by said member, a moving element pivotally supported by said member, a controi spring stud supported by said member and insulated therefrom, a control spring secured to said moving element and to said stud, and a zero shifting means for moving said stud with respect to said member.

20. An electrical measuring instrument comprising a permanent magnet, a tubular non-magnetic member positioned between the ends of said magnet, two inwardly extending and op ositely positioned tongues near each end of said member, a spring clip having its ends sprung beneath the two tongues near each end of said member, a cup mounted on each. end of said member,a pivot bearing threaded in each cap and having a shoulder engagin the spring clip so that the clip is positionet l between the cap and the shoulder, and it movin element mounted between said pivot bearings.

21. An electrical measuring instrument comprising a permanent magnet, a tubular non-magnetic member positioned between the ends of said magnet, two inwardly extending and oppositely positioned tongues near each end of said member, a spring clip having its ends sprung beneath the two tongues nea r each end of said member, a cap mounted on each end of said member, a

pivot bearin threaded in each cap and ha'Q-' ing a shook or engaging the spring clip ad that the clip is positioned between the cap and the shoulder, a moving element mounted between said pivot bearings, a control spring stud securedto each cap and insulated therefrom, and a control sprin secured to each stud and to said moving e ement.

22. An electrical measurlng instrument comprising a permanent magnet, a tubular non-magnetic member positioned between the ends of said magnet, twp inwardly extending and oppositely positioned tongues near each endo said member, a springclip having its ends sprung beneath the two tongues near each end of said member, a cap mounted on curl] end of said member, a pivot bearing threaded in each cap and having a shoulder engaging the spring rlip so that the clip positioned hetwoen the cap and tho shonltlcr a moving element HlOllllltll hetwvun said pivot bearings, a control spring atlHl r-NHlfli 11o rarh cap and insulated thorel'roin. a nontrol npring secured helm-r11 ('tHll stud and said moving element. and a Y-(l'U shifting means for moving one ol said rapwith resperl to saitl monihm'.

23. An electrical measuring iintrnniont comprising a permanent niagnoi, inning cut-Yeti Finis. :1 ovlinllriral slnll ol nonmagnetir n'iaterial positiont-tl hotwoon the carved ends of said nnngnct a spherical nmgnetir core positioned within said shell and littni-nn the ends o l" Haiti magnet, two in n'artlly extending and opponltrl) posit lfillt't'l tongue, near earl: 0nd of said shel za nt tongues loring integral with the matrrial ol' the Hlllll. a w ring rlip having its enlin sprang beneath the two tongnos nvznillCll mid of saitl shrll. a rap mounted on each uinl of said slit-ll, a pivot. hearing ll)1'0tlLl((i in earl: rap anrl having a shoulder engaging the spring clip so that the clip is POSlilOllltl hrtwenn the rap and the shoulder, and a moving element mounted between said pivot bearings.

An electrical measuring instrument comprising a permanent magnet having curved ends. a cylindrical shell of nonmagnetic material positioned betwcen the carved (aide: of said magnet, a spherical magnetic core positioned within said shell and between the main of said magnet and nnpporb eil hy the shall, two inwardly extruding and oppositely positioned tongues near each and of said shrii. said tongnos being integral with the matrrial of the shell. :1 spring clip having its ends sprung beneath the two iongnes near Bilt'll end of said shell. :1 cap mounted on uarh rntl of said shell. a pivot: hearing; illluuilfll in oach rap and having a SllOltlllil' engaging tho spring tlinso that tho (*Ei'n is positioned hrtnci-n tlnriran and tho shonhioi: a mowing elonn'nt mounted liriAYBiIl said PM at hrarings ZlllLl having a cir- LUlill' current arrying coii arrangvil within l'hr shell and around bztlkl corn: :1 rontrol spring sithi bQtlltll to rat-n ca :nnl lllh'lb latml therefrom. a ta'mtrol spring Stliil'lll to each stinl and to aid moving tllilliilt. and a zero Shifting means for moving one of said raps with respect to mill :nrmlirh In wit nrss: wherroi', l haw llif'lflllliti H'l my hand tin; 23rd day of Na will. 

